The crash left the bus lying on its side on the guardrail of Interstate 80 in Mount Olive, its undercarriage and front end sheared off and its steering wheel exposed. Some of the victims crawled out of the emergency exit in the back and an escape hatch on the roof. More than 40 people were taken to hospitals.

Fifth-grade student Theo Ancevski, who was sitting in the fourth row of the bus and was treated at a hospital for cuts and scrapes, said he heard a scraping sound and the bus "toppled over."

"A lot of people were screaming and hanging from their seatbelts," he said.

Gov. Phil Murphy said one adult and one student were killed. Their names had not been released. Murphy said the truck driver was hospitalized, but officials didn't reveal his condition.

The front end of the red dump truck was mangled in the wreck, which took place about 50 miles (80 kilometers) west of New York. The truck was registered to Mendez Trucking, of Belleville, and had "In God We Trust" emblazoned on the back of it.

The bus had entered westbound Interstate 80 from southbound U.S. Highway 206, police said. Cleanup crews loaded its wreckage onto a flat-bed truck on Thursday night as they cleared the roadway.

Police didn't release details of how the crash happened, but the trucking company had a string of crashes in recent years and a higher than average rate of violations that sidelined its vehicles, according to federal safety data.

There were 45 people, including 38 students, on the bus. Forty-three people from the bus and the truck driver were hospitalized, some in critical condition.

The bus was owned by the school district and had seatbelts, according to Paramus schools superintendent Michele Robinson. There is no federal requirement for seatbelts on full-sized school buses, but six states including New Jersey require them.

The bus was one of three taking students from East Brook Middle School to Waterloo Village, a historic site depicting a Lenape Indian community and once-thriving port about 5 miles (8 kilometers) from the crash scene. The other buses made it to the site but returned to the school about 50 miles (80 kilometers) away.

Some of the children were inside the bus and some were outside when first responders arrived, said Jeff Paul, director of the Morris County Office of Emergency Management.

"We had patients laying all over the median and on the interstate," Paul said. "There were all kinds of injuries, every injury type you could expect in a crash of this magnitude."

Thuy Nguyen, a nurse from Paramus, said she rushed to the school, where her son was taking a test after hearing the news.

"My heart just dropped. You hear the name of the school ... ," she said before trailing off.

Robinson said the district was cancelling school trips for the rest of the year.

Mendez Trucking has about 40 drivers and trucks, according to the Federal Motor Carrier Safety Administration. Its trucks had been in seven crashes, none fatal, during the last two years before Thursday's crash, the FMCSA says. Messages left with the company weren't returned.

Mendez has a higher than average vehicle out-of-service rate, which means inspections found violations that had to be corrected before the vehicles could be returned to service. Mendez's rate was 37.9 percent, according to the FMCSA, while the national average is 20.7 percent.

A Mendez-owned dump truck driven by a driver police say had a suspended license struck and killed a French fashion stylist in New York in January 2011, according to court records.

According to the National Highway Traffic Safety Administration, 118 people on school buses were killed in crashes from 2007 to 2016, the last year for which data is available. Of those killed, 68 were passengers, including 58 school-age children, and 50 were drivers. School bus crashes killed 902 people in other vehicles over that span.

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Porter reported from Morristown, and Sisak reported from Philadelphia. Associated Press writers Shawn Marsh in Trenton, Mike Catalini in Paramus and Christina Paciolla, Jeff McMillan, Alexandra Villarreal and Claudia Lauer in Philadelphia contributed to this report as did investigative researcher Randy Herschaft in New York.